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A double-strand break repair model refers to the various models of pathways that cells undertake to repair double strand-breaks (DSB). DSB repair is an important cellular process, as the accumulation of unrepaired DSB could lead to chromosomal rearrangements, tumorigenesis or even cell death. [ 1 ]
[70] γH2AX (H2AX phosphorylated on serine 139) can be detected as soon as 20 seconds after irradiation of cells (with DNA double-strand break formation), and half maximum accumulation of γH2AX occurs in one minute. [70] The extent of chromatin with phosphorylated γH2AX is about two million base pairs at the site of a DNA double-strand break.
[52] γH2AX (H2AX phosphorylated on serine 139) can be detected as soon as 20 seconds after irradiation of cells (with DNA double-strand break formation), and half maximum accumulation of γH2AX occurs in one minute. [52] The extent of chromatin with phosphorylated γH2AX is about two million base pairs at the site of a DNA double-strand break.
In the fruitfly Drosophila, irradiation of germ line cells generates double-strand breaks that result in cell cycle arrest and apoptosis. The Drosophila CHEK2 ortholog mnk and the p53 ortholog dp53 are required for much of the cell death observed in early oogenesis when oocyte selection and meiotic recombination occur. [16]
Recombination, in this model, is initiated by a double-strand break (or gap) shown in the DNA molecule (chromatid) at the top of the figure. Other types of DNA damage may also initiate recombination. For instance, an inter-strand cross-link (caused by exposure to a cross-linking agent such as mitomycin C) can be repaired by HRR.
The double-strand damages include double-strand breaks (DSBs) and inter-strand crosslinks. For humans, the estimated average number of endogenous DNA DSBs per cell occurring at each cell generation is about 50. [27] This level of formation of DSBs likely reflects the natural level of damages caused, in large part, by ROS produced by active ...
[38] γH2AX (H2AX phosphorylated on serine 139) can be detected as soon as 20 seconds after irradiation of cells (with DNA double-strand break formation), and half maximum accumulation of γH2AX occurs in one minute. [38] The extent of chromatin with phosphorylated γH2AX is about two million base pairs at the site of a DNA double-strand break.
A double-strand break is a kind of DNA damage in which both strands in the double helix are severed. DSBs only occur during DNA replication of the cell cycle.Furthermore, DSBs can lead to genome rearrangements and instability. [3]